1. Field of the Invention
This invention relates to an electrochemical process and apparatus to disassociate metal oxides into oxygen and the metal or metals; and more particularly to a process and apparatus for electrochemical generation of metals or metals from metal oxides including ion conductors to isolate the activity at the electrodes from chemical reaction and the regeneration of the metal which acts to electrochemically displace the metal of the metal oxide.
2. Background of the Invention
A number of solid ion conductors have been developed recently. Solid ion conductors may be either anion or cation conductors; ZrO.sub.2 is an example of the former, and .beta.-alumina is an example of the latter. For the most part, these have been applied as sensors. Applications of these sensors include measuring parts per million of levels of oxygen in inert gases and the oxygen activity in molten steel. An example of a cation conductor used at high current density is the .beta.-alumina used in the Na-S battery. The scientific principles for solid ion conductors are well established. Finding new conductors or using some modifications of known conductors for new applications such as for reducing metal oxides is an endeavor worthy of support.
When normal oxide reductions are carried out by pyrochemical means, a waste oxide byproduct is produced by the chemical combination of the reductant metal and metal oxide. The development of ion conductors and electrochemical metal oxide reduction systems which utilize the ion conductors could have wide application not only in the nuclear industry, but also in the metals production industry since the waste product can be easily regenerated producing an oxygen gas stream, which can be vented, and new reductant metal.
As used in the specification and appended claims, the terms metal oxide and reductant are defined as follows.
Metal oxide is the oxide of a metal from which the desired metal product is to be obtained. For example: EQU UO.sub.2 .fwdarw.U.
Reductant is the metal (a different metal) which chemically reacts with the metal oxide to produce reductant metal oxide and metal products. For example: EQU Ca.sub.(reductant) +1/2UO.sub.2 .fwdarw.CaO+U.sub.(product).
Accordingly, it is an object of the present invention to provide an electrochemical process and an electrochemical cell for reducing a metal oxide using ion conductors.
It is another object of the invention to provide an improved electrochemical process and an electrochemical cell for reducing a metal oxide overcoming some of the disadvantages of known arrangements for reducing metal oxides.
It is another object of the invention to provide an electrochemical process and associated apparatus used to disassociate reductant metal oxides into oxygen and the reductant metal or metals, for example to generate Ca.degree. from CaO, using ion conductors to isolate the activity at the electrodes from chemical reaction and the regeneration of the reductant metal which acts to chemically displace the metal of the metal oxide.
It is another object of the invention to use ion conductors applied in electrochemical processes to separate oxygen from the waste product and to regenerate the reductant metal for recycle.
It is another object of the invention to use ion conductors applied in electrochemical processes to clean up waste salts, for example, produced in the weapons program, which are contaminated with actinide oxides.